| 1 | <?xml version="1.0" encoding="UTF-8"?> |
| 2 | <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN" |
| 3 | "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd"> |
| 4 | <refentry id="glDrawArraysInstanced"> |
| 5 | <refmeta> |
| 6 | <refmetainfo> |
| 7 | <copyright> |
| 8 | <year>2010</year> |
| 9 | <holder>Khronos Group</holder> |
| 10 | </copyright> |
| 11 | </refmetainfo> |
| 12 | <refentrytitle>glDrawArraysInstanced</refentrytitle> |
| 13 | <manvolnum>3G</manvolnum> |
| 14 | </refmeta> |
| 15 | <refnamediv> |
| 16 | <refname>glDrawArraysInstanced</refname> |
| 17 | <refpurpose>draw multiple instances of a range of elements</refpurpose> |
| 18 | </refnamediv> |
| 19 | <refsynopsisdiv><title>C Specification</title> |
| 20 | <funcsynopsis> |
| 21 | <funcprototype> |
| 22 | <funcdef>void <function>glDrawArraysInstanced</function></funcdef> |
| 23 | <paramdef>GLenum <parameter>mode</parameter></paramdef> |
| 24 | <paramdef>GLint <parameter>first</parameter></paramdef> |
| 25 | <paramdef>GLsizei <parameter>count</parameter></paramdef> |
| 26 | <paramdef>GLsizei <parameter>primcount</parameter></paramdef> |
| 27 | </funcprototype> |
| 28 | </funcsynopsis> |
| 29 | </refsynopsisdiv> |
| 30 | <refsect1 id="parameters"><title>Parameters</title> |
| 31 | <variablelist> |
| 32 | <varlistentry> |
| 33 | <term><parameter>mode</parameter></term> |
| 34 | <listitem> |
| 35 | <para> |
| 36 | Specifies what kind of primitives to render. Symbolic constants <constant>GL_POINTS</constant>, |
| 37 | <constant>GL_LINE_STRIP</constant>, <constant>GL_LINE_LOOP</constant>, <constant>GL_LINES</constant>, |
| 38 | <constant>GL_TRIANGLE_STRIP</constant>, <constant>GL_TRIANGLE_FAN</constant>, <constant>GL_TRIANGLES</constant> |
| 39 | <constant>GL_LINES_ADJACENCY</constant>, <constant>GL_LINE_STRIP_ADJACENCY</constant>, |
| 40 | <constant>GL_TRIANGLES_ADJACENCY</constant>, <constant>GL_TRIANGLE_STRIP_ADJACENCY</constant> and <constant>GL_PATCHES</constant> |
| 41 | are accepted. |
| 42 | </para> |
| 43 | </listitem> |
| 44 | </varlistentry> |
| 45 | <varlistentry> |
| 46 | <term><parameter>first</parameter></term> |
| 47 | <listitem> |
| 48 | <para> |
| 49 | Specifies the starting index in the enabled arrays. |
| 50 | </para> |
| 51 | </listitem> |
| 52 | </varlistentry> |
| 53 | <varlistentry> |
| 54 | <term><parameter>count</parameter></term> |
| 55 | <listitem> |
| 56 | <para> |
| 57 | Specifies the number of indices to be rendered. |
| 58 | </para> |
| 59 | </listitem> |
| 60 | </varlistentry> |
| 61 | <varlistentry> |
| 62 | <term><parameter>primcount</parameter></term> |
| 63 | <listitem> |
| 64 | <para> |
| 65 | Specifies the number of instances of the specified range of indices to be rendered. |
| 66 | </para> |
| 67 | </listitem> |
| 68 | </varlistentry> |
| 69 | </variablelist> |
| 70 | </refsect1> |
| 71 | <refsect1 id="description"><title>Description</title> |
| 72 | <para> |
| 73 | <function>glDrawArraysInstanced</function> behaves identically to <citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry> |
| 74 | except that <parameter>primcount</parameter> instances of the range of elements are executed and the value of the internal counter |
| 75 | <parameter>instanceID</parameter> advances for each iteration. <parameter>instanceID</parameter> is an internal 32-bit integer counter |
| 76 | that may be read by a vertex shader as <constant>gl_InstanceID</constant>. |
| 77 | </para> |
| 78 | <para> |
| 79 | <function>glDrawArraysInstanced</function> has the same effect as: |
| 80 | <programlisting><![CDATA[ if ( mode or count is invalid ) |
| 81 | generate appropriate error |
| 82 | else { |
| 83 | for (int i = 0; i < primcount ; i++) { |
| 84 | instanceID = i; |
| 85 | glDrawArrays(mode, first, count); |
| 86 | } |
| 87 | instanceID = 0; |
| 88 | }]]></programlisting> |
| 89 | </para> |
| 90 | </refsect1> |
| 91 | <refsect1 id="errors"><title>Errors</title> |
| 92 | <para> |
| 93 | <constant>GL_INVALID_ENUM</constant> is generated if <parameter>mode</parameter> is not one of |
| 94 | the accepted values. |
| 95 | </para> |
| 96 | <para> |
| 97 | <constant>GL_INVALID_OPERATION</constant> is generated if a geometry shader is active and <parameter>mode</parameter> |
| 98 | is incompatible with the input primitive type of the geometry shader in the currently installed program object. |
| 99 | </para> |
| 100 | <para> |
| 101 | <constant>GL_INVALID_VALUE</constant> is generated if <parameter>count</parameter> or <parameter>primcount</parameter> are negative. |
| 102 | </para> |
| 103 | <para> |
| 104 | <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to an |
| 105 | enabled array and the buffer object's data store is currently mapped. |
| 106 | </para> |
| 107 | </refsect1> |
| 108 | <refsect1 id="seealso"><title>See Also</title> |
| 109 | <para> |
| 110 | <citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry>, |
| 111 | <citerefentry><refentrytitle>glDrawElementsInstanced</refentrytitle></citerefentry> |
| 112 | </para> |
| 113 | </refsect1> |
| 114 | <refsect1 id="Copyright"><title>Copyright</title> |
| 115 | <para> |
| 116 | Copyright <trademark class="copyright"></trademark> 2010 Khronos Group. |
| 117 | This material may be distributed subject to the terms and conditions set forth in |
| 118 | the Open Publication License, v 1.0, 8 June 1999. |
| 119 | <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>. |
| 120 | </para> |
| 121 | </refsect1> |
| 122 | </refentry> |